Retire can_return_tt() and rewirte TT-hit code

[stockfish] / src / search.cpp

diff --git a/src/search.cpp b/src/search.cpp
index 4fd6c899de47446b182807e98d3314fb5516ddc7..a3d8781889a690e15e0b91c4044c0243245f90d1 100644 (file)
--- a/src/search.cpp
+++ b/src/search.cpp
@@ -104,36 +104,11 @@ namespace {
   bool connected_moves(const Position& pos, Move m1, Move m2);
   Value value_to_tt(Value v, int ply);
   Value value_from_tt(Value v, int ply);
-  bool can_return_tt(const TTEntry* tte, Depth depth, Value ttValue, Value beta);
   bool connected_threat(const Position& pos, Move m, Move threat);
   Value refine_eval(const TTEntry* tte, Value ttValue, Value defaultEval);
   Move do_skill_level();
   string uci_pv(const Position& pos, int depth, Value alpha, Value beta);
 
-  // is_dangerous() checks whether a move belongs to some classes of known
-  // 'dangerous' moves so that we avoid to prune it.
-  FORCE_INLINE bool is_dangerous(const Position& pos, Move m, bool captureOrPromotion) {
-
-    // Castle move?
-    if (type_of(m) == CASTLE)
-        return true;
-
-    // Passed pawn move?
-    if (   type_of(pos.piece_moved(m)) == PAWN
-        && pos.pawn_is_passed(pos.side_to_move(), to_sq(m)))
-        return true;
-
-    // Entering a pawn endgame?
-    if (    captureOrPromotion
-        &&  type_of(pos.piece_on(to_sq(m))) != PAWN
-        &&  type_of(m) == NORMAL
-        && (  pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK)
-            - PieceValue[Mg][pos.piece_on(to_sq(m))] == VALUE_ZERO))
-        return true;
-
-    return false;
-  }
-
 } // namespace
 
 
@@ -199,8 +174,9 @@ void Search::think() {
   Position& pos = RootPosition;
   Chess960 = pos.is_chess960();
   Eval::RootColor = pos.side_to_move();
-  Eval::ValueDraw[ Eval::RootColor] = VALUE_DRAW - Eval::ContemptFactor;
-  Eval::ValueDraw[~Eval::RootColor] = VALUE_DRAW + Eval::ContemptFactor;
+  int scaledCF = Eval::ContemptFactor * MaterialTable::game_phase(pos) / PHASE_MIDGAME;
+  Eval::ValueDraw[ Eval::RootColor] = VALUE_DRAW - Value(scaledCF);
+  Eval::ValueDraw[~Eval::RootColor] = VALUE_DRAW + Value(scaledCF);
   TimeMgr.init(Limits, pos.startpos_ply_counter(), pos.side_to_move());
   TT.new_search();
   H.clear();
@@ -567,8 +543,11 @@ namespace {
     // a fail high/low. Biggest advantage at probing at PV nodes is to have a
     // smooth experience in analysis mode. We don't probe at Root nodes otherwise
     // we should also update RootMoveList to avoid bogus output.
-    if (!RootNode && tte && (PvNode ? tte->depth() >= depth && tte->type() == BOUND_EXACT
-                                    : can_return_tt(tte, depth, ttValue, beta)))
+    if (   !RootNode
+        && tte && tte->depth() >= depth
+        && (           PvNode ?  tte->type() == BOUND_EXACT
+            : ttValue >= beta ? (tte->type() & BOUND_LOWER)
+                              : (tte->type() & BOUND_UPPER)))
     {
         TT.refresh(tte);
         ss->currentMove = ttMove; // Can be MOVE_NONE
@@ -800,10 +779,17 @@ split_point_start: // At split points actual search starts from here
                         << " currmovenumber " << moveCount + PVIdx << sync_endl;
       }
 
+      ext = DEPTH_ZERO;
       captureOrPromotion = pos.is_capture_or_promotion(move);
       givesCheck = pos.move_gives_check(move, ci);
-      dangerous = givesCheck || is_dangerous(pos, move, captureOrPromotion);
-      ext = DEPTH_ZERO;
+      dangerous =   givesCheck
+                 || pos.is_passed_pawn_push(move)
+                 || type_of(move) == CASTLE
+                 || (   captureOrPromotion // Entering a pawn endgame?
+                     && type_of(pos.piece_on(to_sq(move))) != PAWN
+                     && type_of(move) == NORMAL
+                     && (  pos.non_pawn_material(WHITE) + pos.non_pawn_material(BLACK)
+                         - PieceValue[Mg][pos.piece_on(to_sq(move))] == VALUE_ZERO));
 
       // Step 12. Extend checks and, in PV nodes, also dangerous moves
       if (PvNode && dangerous)
@@ -843,7 +829,8 @@ split_point_start: // At split points actual search starts from here
           && !inCheck
           && !dangerous
           &&  move != ttMove
-          && (bestValue > VALUE_MATED_IN_MAX_PLY || bestValue == -VALUE_INFINITE))
+          && (bestValue > VALUE_MATED_IN_MAX_PLY || (   bestValue == -VALUE_INFINITE
+                                                     && alpha > VALUE_MATED_IN_MAX_PLY)))
       {
           // Move count based pruning
           if (   depth < 16 * ONE_PLY
@@ -1110,7 +1097,10 @@ split_point_start: // At split points actual search starts from here
     // only two types of depth in TT: DEPTH_QS_CHECKS or DEPTH_QS_NO_CHECKS.
     ttDepth = inCheck || depth >= DEPTH_QS_CHECKS ? DEPTH_QS_CHECKS : DEPTH_QS_NO_CHECKS;
 
-    if (!PvNode && tte && can_return_tt(tte, ttDepth, ttValue, beta))
+    if (   tte && tte->depth() >= ttDepth
+        && (           PvNode ?  tte->type() == BOUND_EXACT
+            : ttValue >= beta ? (tte->type() & BOUND_LOWER)
+                              : (tte->type() & BOUND_UPPER)))
     {
         ss->currentMove = ttMove; // Can be MOVE_NONE
         return ttValue;
@@ -1434,20 +1424,6 @@ split_point_start: // At split points actual search starts from here
   }
 
 
-  // can_return_tt() returns true if a transposition table score can be used to
-  // cut-off at a given point in search.
-
-  bool can_return_tt(const TTEntry* tte, Depth depth, Value v, Value beta) {
-
-    return   (   tte->depth() >= depth
-              || v >= std::max(VALUE_MATE_IN_MAX_PLY, beta)
-              || v < std::min(VALUE_MATED_IN_MAX_PLY, beta))
-
-          && (   ((tte->type() & BOUND_LOWER) && v >= beta)
-              || ((tte->type() & BOUND_UPPER) && v < beta));
-  }
-
-
   // refine_eval() returns the transposition table score if possible, otherwise
   // falls back on static position evaluation.